Flush door brace



Nov. 8, 1955 J. CARLOW FLUSH DOOR BRACE Filed June 15, 1953 INVENTOR.

ArmeA/Ey (Inez 64240144 United States Patent O FLUSH DOOR BRACE Jack Carlow, Los Angeles, Calif.

Application June 15, 1953, Serial No. 361,722

12 Claims. (CI. 20-38) This invention relates generally to doors and similar closures, and more particularly to improvements in flush type doors. Specifically, the invention pertains to a prestressed door capable of withstanding stresses which might tend to cause warping.

Hollow doors currently in use are subject to warping which not only detracts from their appearance but results in mal-fitting of the door in its frame. The warping is usually local in character, that is, it may occur in the components of the door, for example in the top or bottom rails, the stiles or the center lockrail, or in any combination of these door elements. The term warp is employed in the building and lumber milling trades to designate any variation from a true or plane surface and includes crook, bow, cup and twist, or any combination of these conditions. It is frequently used to describe a combination of two or more of the above. Crook is a deviation edgewise from a straight line drawn from end to end of a piece; bow is a deviation flatwise from a straight line drawn from end to end of a piece; cup is a curve across the grain or width of a piece; and cross-bow and cross-cup which are forms of twisting are used to designate tortuosity in the piece. In a door, crooking may result in one or both of the stiles curving laterally outwardly in the plane. of the' door. Bowing occurring in stiles may cause the door to assume a condition in which either of its nominally flat sides becomes curved or convexed lengthwise of the door. Cupping present in the upper or lower rails may result in convexity of the upper or lower horizontal edges of the door. Cross-bowing will result in tm'sting of the door about a horizontal axis. Cross-cupping results. in twisting of the door about a vertical axis.

Various expedients have been proposed for reinforcing the door in an effort to reduce or eliminate such crooking, bowing, cupping, cross-bowing and cross-cupping. While some of these expedients have proved quite eflicient in preventing one or more of these kinds of warping, no satisfactory devices have been produced by which all of warping in eliminated.

It is therefore an object of this invention to provide a hollow door having means embodied therein for preventing all of the several factors discussed above which contribute to distortion or warping of the door.

Another object of the invention is to provide a prestressed, warp resistant door of hollow construction in which tension members in the nature of diagonal ties are embodied. The tension is accomplished effectively by means of guys, one pair being located in. the space above the lockrail and the other pair disposed in the space below the lockrail. The legs of the individual V-shaped wires of each pair extend from the lockrail to the ends of one of the rails and are joined thereto at opposite sides of the median vertical plane of the door. guy thus diverge from the vertical transverse median plane of the door and the correspondingly inclined legs of the wires cross each other. With this arrangement, the top and bottom rails and the vertical stiles are maintained in The legs of each wire Patented Nov. 8, 1955 true parallelism with respect. to each other and the four corners of the door thus remain true right angles. In addition, crossing of the corresponding wires transversely of the door prevents distortion of the parts in directions transversely of the door so that the sides of the door are maintained flat or planar throughout.

A further object of the invention is to provide a door, of the class specified, which includes means for adjusting the tension of the wires from outside the door structure.

In accordance with this invention there is provided a flush door which is pro-stressed in the several directions in which such variations from the true or plane surfaces of the door normally occur in conventional doors. The pro-stressing is accomplished with tension members consisting of wires tensioned between the central portion of a cross-member or lockrail of the door and the ends of the top and bottom rails of the door. In one embodiment of the invention which is specifically described herein, each tension. wire extends from one end of the top or bottom rail, through a V-shaped groove in a side of the lockrail and thence to the other end of same rail, the wire thus assuming a V configuration with the apex of the V looped through the groove. In a'practical form of the invention metal anchoring means are provided on the lockrail by which the apex portions of the V-shaped wires are joined to the lockrail, this means eifecting metal-to-metal contact so as to prevent the wire from cutting into the wood forming the lockrail. The tension in the wires is adjusted by means of tensioning screws extending inwardly through holes in the rails of the door and to the inner ends of which the free ends of the wires are joined, the screws having slotted heads, accessible from the outside of the door, by which the screws can be rotated to tighten the wires as required. The invention further provides means for preventing twisting of the wires during such rotation of the tensioning screws.

The foregoing and the objects of the invention will appear from the following description and from the drawing, which is for the purpose of illustration only, and in which:

Fig. .1 is a part-sectional, side elevational view of the improved pre stressed door;

Fig. 2 is an enlarged cross-sectional view, taken on line 2-2 of Fig. 1;

Fig. 3 is a composite perspective view, showing the central grooved portion of the lockrail and the associated parts of the anchoring means,

Fig. 4 is a fragmentary perspective view of the apex ends of the V-shaped tension wires, illustrating their relative positions in the grooves in the sides of the lockrail; and.

Fig. 5 is a perspective view of part of the tensioning means.

Referring to the drawing in detail, the improved door includes a pair of spaced vertical members or stiles 10 and 11 which are joined at their upper and lower ends by top and bottom end rails 12 and 13, respectively. Extending between the stiles 10' and 11, substantially midway between their upper and lower ends, is a lockrail 14. For convenience the unit formed by the stiles, the end rails and the lockraiI is sometimes referred to herein as a frame. The door components referred to above are secured together by tongu'es-and-grooves, rabbeted joints or other conventional jointing. means. Reinforcing blocks 15 may be provided at the intersections of the ends of the lockrail 14 and the stiles 10 and 11. The sides of the structure are closed by panels 16 and 17 of. plywood or other selected sheet material. Spacer blocks 18 may be inset between the panels 16 and 17 at selected areas, if desired, and glued in place.

As shown, the lockrail 14 is provided with relatively shallow, inclined grooves 21, 22 and 23 in a side face thereof, the intermediate groove 22 being of a width equal to substantially twice that of either of the other grooves 21 and 23. The grooves 21 and 22 converge toward the bottom edge of the lockrail, thus providing together a V-shaped groove having its apex adjacent to the lower edge of the lockrail. The inclined grooves 22 and 23 converge in an upward direction to provide between them an inverted V-shaped groove, the apex of which is adjacent the upper edge of the lockrail. Grooves 24, 25 and 26, corresponding respectively with the grooves 21, 22 and 23, are provided in the opposite side face of the lockrail, the grooves 24 and 25 converging downwardly to form a V-shaped groove, while the grooves 25 and 26 converge upwardly to form an inverted V-shaped groove. All of the grooves are of the same depth.

Secured to the upper and lower sides of the lockrail 14 are upper and lower bearing plates 30 and 31. The plates 30 and 31 are fastened in place by means of anchor screws 32, of the round head wood screw type, which pass through washers 33 and through holes in the plates to be screwed into holes in the upper and lower edges of the lockrail. It is to be noted that the bearing plates 30 and 31 are of a width equal to the width of the lockrail, less twice the depth of the inclined grooves at the sides of the lockrail. With this arrangement, the longitudinal edges of the plates 30 and 31 are substantially in vertical alignment with the bottom surfaces of the several grooves 21 to 23 and 24 to 26.

The tensioning means of the door comprises four wires 35, 36, 37 and 38 which have high tensile strength, piano wire preferably being employed for the purpose. These wires, which are looped through the V-shaped grooves in the sides of the lockrail 14, are also V-shaped and thus are provided with legs 35a and 35b, 36a and 36b, 37a and 37b, and 38a and 38b. At their apices or crotch portions, the wires 35 to 38 are provided with horizontally bent loops 40 which seat against the outer flat surfaces of the appropriate bearing plates 30 and 31, and which underlie the washers 33. Thus, the loops 40 are firmly joined to the lockrail 14 by the screws 32 which pass through the loops.

As clearly shown in Fig. 1, the upper convergent portions of the legs 35a and 35b are disposed in the respective downwardly divergent grooves 22 and 23. In a like manner, the legs 36a and 36b are disposed in the grooves 21 and 22, the legs 37a and 37b in the grooves 26 and 25, and the legs 38a and 38b in the grooves 25 and 24. The various legs of the wires 35 to 38 extend from the lockrail 14 in the general direction of the grooves in which their convergent legs are held, the lower end of the leg 35a being operatively connected to the lefthand end of the bottom rail 13 and the lower end of the leg 35b being similarly connected to the right-hand end of this rail. The lower ends of the legs 37a and 37b are similarly connected to the respective leftand right-hand ends of the bottom rail 13. The upper ends of the legs 36a and 38a are operatively connected to the left-hand end of the top rail 12 while the legs 36b and 38b are similarly joined to the right-hand end of this rail. The arrangement of the convergent legs of the several wires 35 to 38 at the point of joinder with the lockrail 14 is shown clearly in Fig. 4 of the drawing.

Suitable means are secured to the wires to prevent or minimize vibration noises. Such silencing means may be in the form of blocks 39 of wood glued between adjacent pairs of wires near their crossing points as shown.

As shown in Figs. 1 and 2, the means for connecting the free ends of the several tension wires or guys 35 to 38 to the end rails 12 and 13 comprises a plurality of like tensioning screws 45, each screw extending through a hole in the end rail 12 or 13 and having a head 46 engaging an annular shoulder provided at the inner end of an outer counterbore of the hole (Fig. l). Preferably, washers are arranged between the heads of the screws and the shoulders of the counterbores. The inner ends of the screws 45 are threaded through small nut-like elements 47 carried at the free ends of the wire legs 35a to 38a and 35b to 38b. As shown in Fig. 5, the free ends of the wire legs are looped through holes in the nuts 47 with the wire wound upon itself as indicated at 48, the extremity of the wire then projecting laterally in a finger 49.

It is to be particularly noted that the holes through which the tensioning screws 45 extend are drilled at opposite sides of the longitudinal, vertical median plane passing through the top and bottom rails 12 and 13 and that the holes at each end of the rails are sloped inwardly toward said median plane (Fig. 2). As shown in this view, the various wire legs or guys extend from a side of the lockrail 14 to the tensioning screw 45 located adjacent the opposite side edge of the rail 12 or 13, the corresponding legs 35a, 37a and 35b, 37b and 36a, 38a and 36b, 38b thus crossing each other in the spaces between the lockrail and the end rails, such relation of the legs 35a, 37a being illustrated in Fig. 2. Thus, the wires provide crossing ties or guys which pre-stress the door elements 11, 12, 13 and 14 diagonally both in the plane of the door and in planes transversely thereof.

To adjust the tension of the wires 35 to 38 and thus vary the degree of pre-stressing of the door elements, the tensioning screws 45 are manipulated. During rotation of these screws, the fingers 49 of the wires engage the panels 16, 17 to resist rotation of the nuts 47 and twisting of the wires. It is also to be observed that the V-looped portions of the wires 35 to 38, which are connected to the lockrail, contact the side edges of the bearing plates 30 and 31 so as to prevent the wires from cutting into the wood forming the lockrail. While the divergent wires, for example, those designated 35a and 35b are disclosed as integral legs of a single wire, it is within the concept of the invention to provide separate, unconnected wires for the purpose. However, the use of the single bent stressing wires greatly simplifies the construction by avoiding complicated anchoring devices which would be necessary to fasten the individual wires to the lockrail.

Air vents 50 are formed in the upper and lower end rails 12 and 13 to permit ingress and egress of air to accommodate expansion and contraction thereof due to temperature variations. A door made in accordance with the construction shown in the drawings and described above is substantially proof against warping. This may be attributed to the fact that the tension wires pre-stress the door components to guard against deformation of the wood in the plane of the door and in directions transversely of said plane, the wires cooperating with the rails and stiles to provide, in effect, crossing triangular trusses. For example, the wire legs 35b and 37b form with the lockrail 14 and the lower half of the stile 12 a truss, as do also the wire legs 35a and 37a when viewed in end elevation (Fig. 2). Such tensioned and crossing wires in the lower and upper halves of the door prevent twisting of each half and, hence, twisting of the entire door. Furthermore, with this construction cupping of the rails, bowing and crooking of the stiles, and cross bowing and cross-cupping of the door are all effectively prevented so that warping of the door in any direction due to any of these conditions alone or in combination is effectively prevented. Furthermore, if for any reason, for example, a change in aging or climatic conditions, it becomes necessary to re-adjust the tension of the wires, this is easily accomplished by simply turning the bolts 45 by means of a screwdriver to overcome any warping that has occurred. The effectiveness of my construction depends very largely upon the employment of pairs of crossing tension members that are anchored at the center of the door and at the four corners.

In accordance with the provisions of the patent statutes, I have described the principle of the invention and have disclosed what I now consider to represent the best embodiment of the invention, but I wish it to be understood, however, that the structure shown is only illustrative and that the invention may be carried out by modified means.

I claim as my invention:

1. A pre-stressed door structure, including: opposite vertical stiles; top and bottom rails extending between the upper and lower ends of the stiles; a lockrail extending between said stiles substantially midway between their ends; a plurality of tension members each having an intermediate loop portion connected to the lockrail at a point intermediate the ends thereof, and each having legs extending from said loop portion to opposite ends of said rails; and manually operable means accessible from the exterior of the door structure for tensioning said legs.

2. A pro-stressed door structure, including: opposite vertical stiles; top and bottom rails extending between the upper and lower ends of the stiles; a lockrail extending between said stiles substantially midway between their ends; an upper pair of V-shaped tension members, each member having a loop at its apex connected to said lockrail intermediate the ends thereof and each having divergent, upwardly extending legs operatively connected to opposite ends of said top rail; a lower pair of V-shaped tension members, each member having a loop at its apex connected to said lockrail intermediate the ends thereof and each having divergent, downwardly extending legs operatively connected to opposite ends of said bottom rail; and manually adjustable means accessible from the exterior of said rails for tensioning all of said legs.

3. A pre-stressed door structure, including: opposite vertical stiles; top and bottom rails extending between the upper and lower ends of the stiles; a lockrail extending between said stiles substantially midway between their ends; an upper pair of V-shaped tension members, each member having a loop at its apex connected to said lockrail intermediate the ends thereof and each having divergent, upwardly extending legs operatively connected to opposite ends of said top rail; a lower pair of V-shaped tension members, each member having a loop at its apex connected to said lockrail intermediate the ends thereof and each having divergent, downwardly extending legs operatively connected to opposite ends of said bottom rails; and manually adjustable means accessible from the exterior of said rails for tensioning all of said legs.

4. A pre-stressed door structure, including: opposite vertical stiles; top and bottom rails extending between the upper and lower ends of the stiles; a lockrail extending between said stiles substantially midway between their ends; an upper pair of V-shaped tension members, each member having a loop at its apex connected to said lockrail intermediate the ends thereof and each having divergent, upwardly extending legs operatively connected to opposite ends of said top rail; and a lower pair of V-shaped tension members, each member having a loop at its apex connected to said lockrail intermediate the ends thereof and each having divergent, downwardly extending legs operatively connected to opposite ends of said bottom rail; the corresponding legs of said tension members which extend to the same end of a said rail crossing each other and being operatively connected to said same end at points adjacent opposite vertical sides of said same end.

5. A pre-stressed door structure, including: opposite vertical stiles; top and bottom rails extending between the upper and lower ends of the stiles; a lockrail extending between said stiles substantially midway between their ends; a first V-shaped tension member having its apex portion secured to said lockrail and having downwardly divergent legs disposed at the front side of said lockrail with their lower ends operatively connected to opposite ends of said bottom rail adjacent the rearward side thereof; a second V-shaped tension member having its apex portion secured to said lockrail and having upwardly divergent legs disposed at the front side of saidlocl trail with their upper ends operatively connected to opposite ends of said top rail adjacent the rearward side thereof; a third V-shaped tension member having its apex portion secured to said lockrail and having downwardly divergent legs disposed at the rearward side of said lockrail with theirlower ends operatively connected to opposite ends of said bottom rail adjacent the forward side thereof; a fourth V-shaped tension member having its apex portion secured to said lockrail and having upwardly divergent legs disposed at the rearward side of said lockrail with their upper ends operatively connected to opposite ends of said top rail adjacent the forward side thereof, the corresponding legs of tension members connected to the same ends of said rails thus crossing each other; and manually adjustable means accessible from the exterior of said rails for tensioning each of said legs.

6. A door structure as defined in claim 5 in which said lockrail has inclined grooves in its sides in which the portions of all of said legs adjacent said apices are disposed.

7. A door structure as defined in claim 5 in which said lockrail has inclined grooves in its sides in which the portions of all of said legs adjacent said apices are disposed, said apex portions of said first and third tension members having laterally extending loops secured against the upper edge of said lockrail at substantially the longitudinal center thereof and said apex portions of said second and fourth tension members having laterally extending loops secured against the bottom edge of said lockrail at substantially the longitudinal center thereof.

8. A door structure as defined in claim 5 in which said lockrail has inclined grooves in its sides in which the portions of all of said legs adjacent said apices are disposed, said apex portions of said first and third tension members having laterally extending loops secured against the upper edge of said lockrail at substantially the longitudinal center thereof and said apex portions of said second and fourth tension members having laterally extending loops secured against the bottom edge of said lockrail at substantially the longitudinal center thereof, the structure further including plates disposed against said top and bottom edges of said lockrail and anchor screws extending through holes in said plates and screwed into said lockrail, said loops embracing said screws and being secured thereby against said plates.

9. A door structure as defined in claim 5 in which said lockrail has inclined grooves in its sides in which the portions of all of said legs adjacent said apices are disposed, said apex portions of said first and third tension members having laterally extending loops secured against the upper edge of said lockrail at substantially the longitudinal center thereof and said apex portions of said second and fourth tension members having laterally extending loops secured against the bottom edge of said lockrail at substantially the longitudinal center thereof, the structure further including plates disposed against said top and bottom edges of said lockrail and anchor screws extending through holes in said plates and screwed into said lockrail, said loops embracing said screws and being secured thereby against said plates, the legs of said members engaging against the side edges of said plates and being spaced thereby outwardly of the bottom surfaces of said grooves in said lockrail.

10. A door structure as defined in claim 5 in which said manually adjustable means consists of a bolt extending inwardly through a hole in a said rail, and a nut element screwed onto the inner threaded end of said bolt and fastened to the end of a said leg, rotation of said bolt varying the tension applied to said leg.

11. A door structure as defined in claim 5 in which said manually adjustable means consists of a bolt extending inwardly through a hole in a said rail, said bolt having a head engaging the inner end of an outer counterbore of said hole, and a nut element screwed onto the 7 inner threaded end of said bolt and fastened to the end of a said leg, rotation of said bolt varying the tension applied to said leg.

12. A door structure as defined in claim 5 in which said manually adjustable means consists of a bolt extending inwardly through a hole in a said rail, said bolt having a head engaging the inner end of an outer counterbore of said hole, and a nut element screwed onto the inner threaded end of said bolt and fastened to the end of a said leg, rotation of said bolt varying the tension applied to said leg, and laterally extending means on said leg engaging a part of said door structure for preventing rotation of said leg and said nut element.

References Cited in the file of this patent UNITED STATES PATENTS 1,128,848 Christensen Feb. 16, 1915 1,393,611 Carle Oct. 11, 1921 2,386,098 Englund Oct. 2, 1945 2,578,240 Green et a1. Dec. 11, 1951 

